Delivery system and method for interstitial radiation therapy

ABSTRACT

A delivery system and method for interstitial radiation therapy comprising a substantially axially stiff and longitudinally flexible elongated member made of material, which is bio-absorbable in living tissue and a plurality of radioactive seeds dispersed in a predetermined array within the member. The delivery system and method further customize the member based on a prescription.

Provisional Patent Application priority claim.

[0001] This application claims priority to U.S. Provisional PatentApplication No. ______, filed Nov. 2, 2001 under 35 U.S.C. §119(e).

FIELD OF INVENTION

[0002] The present invention relates to systems and methods fordelivering a plurality of radioactive sources to a treatment site.

BACKGROUND

[0003] In interstitial radiation therapy, one method for treating tumorsis to permanently place small, radioactive seeds into the tumor site.This method is currently accomplished by one of the following twoprocedures: (a) loose seeds are implanted in the target tissue, and/or(b) seeds are contained within a woven or braided absorbable carriersuch as braided suture material and implanted in the target tissue. Theloose seeds, however, are dependent on the tissue itself to hold eachindividual seed in place during treatment, and the woven or braidedsutures do not assist in the placement of the seeds relative to thetarget tissue.

[0004] There have been many developments in brachytherapy (i.e. therapyrelating to treating malignant tumors for handling such radioactiveseeds). In one technique, hollow metal needles are inserted into thetumor and the seeds are thereafter inserted into the needles, while theneedles are being retracted to deposit the seeds in the tumor. Suchdevices are shown in U.S. Pat. No. 4,402,308 which is incorporatedherein by reference. The most commonly used instruments are the Henschkeand Mick devices. The use of such devices has distinct disadvantages.The overall length of such devices is over 20 cm and such devices havesignificant weight making them difficult to manipulate.

[0005] Another disadvantage of the above technique is that the seeds aredeposited in a track made by the needle. When the needle is withdrawn,there is a tendency for the seeds to migrate in that track resulting ina poor distribution of the seeds. Because the energy levels are low,distribution between centers of adjacent seeds should be on the order ofabout 1 cm for certain treatments. Poor distribution of seeds can resultin undesirable concentrations of seeds resulting in either anover-dosage or under-dosage of radiation. Further, over time, the seedstend to migrate along the needle track, away from the tumor, andaccordingly patients commonly must repeat the procedure within a couplemonths to have seeds re-implanted near the tumor.

[0006] Further complicating the procedure is the fact that the seeds aresmall, because they need to fit in small bore needles to preventexcessive tissue damage. Due to their small size and high seed surfacedose, the seeds are difficult to handle and to label, and can easily belost. In addition, the technique of implantation of individual seeds istime consuming.

[0007] One preferred method of introducing seeds into the tumor site isusing a pre-manufactured elongated assembly or implant that containsseeds spaced at 1 cm increments. This assembly is capable of beingloaded into an introducer needle just prior to the procedure. What isdesired in using an elongated assembly of seeds and spacers is theability to insert such an assembly into a tumor site to providecontrolled and precise placement of the radioactive seeds.

[0008] While assemblies with bio-absorbable materials and spacedradioactive seeds are known for use as interstitial implants, suchassemblies are not entirely satisfactory. In one instance, the elongatedimplant is made using a bio-absorbable material consisting of an EthiconVicryl.RTM. This material is commonly known as PGA. Radioactive seedsand teflon spacers are inserted into the material. Needles loaded withthe seeds in the carrier bio-absorbable material are sterilized orautoclaved causing contraction of the carrier material and resulting ina rigid column of seeds and spacers. This technique was reported in“Ultrasonically Guided Transperineal Seed Implantation of the Prostate:Modification of the Technique and Qualitative Assessment of Implants” byVan't Riet, et al., International Journal of Radiation Oncology, Biologyand Physics, Vol. 24, No. 3, pp. 555-558, 1992 which is incorporatedherein by reference. Such rigid implants have many drawbacks, includingnot having the ability to flex with the tissue over the time that thebio-absorbable material dissolves.

[0009] As the tissue or glands shrink back to pre-operative size, andthus as the tissue recedes, a rigid elongated implant does not move withthe tissue, but remain stationary relative to the patient. The finallocation relative to the tumor is thus not maintained and the dosage ofthe radioactive seeds does not meet the preoperative therapy plan.

[0010] Another system for providing an elongated implant havingradioactive seeds disposed therein is disclosed in U.S. Pat. No.4,697,575 which is incorporated herein by reference. In this reference,a plurality of encapsulated radioactive seeds are positioned in apredetermined array. The seeds are encapsulated in individual capsules,with each capsule having a projection on one capsule end and acomplementary recess on the remaining capsule end. A projection in onecapsule is engageable with a recess in an adjacent capsule such that thedesired number of seeds can be plugged together to form a column ofrigid, bio-absorbable and elongated material. This implant is notentirely satisfactory inasmuch as it is time consuming and inefficientto carry out the manipulative steps of assembling such a strand ofelongated material. Further the implant is quite rigid as it is insertedinto a patient without the use of an introduction needle, as the implantitself acts as a rigid needle that is undesirably left in place.

[0011] In another embodiment disclosed in the above patent, a rigidneedle implant containing radioactive segments, with break points, isinserted into the tumor. The needle implant is made of a bio-absorbablepolymer that is rigid enough to be driven into the tumor withoutdeflection and without the use of a separate hollow needle. When theproper depth is reached with the rigid polymer needle, the remaining,uninserted portion of the needle is broken off. This embodiment has thedisadvantage of the above embodiment, in that being too rigid, theimplant does not follow the tumor as it shrinks back to its normal size.

[0012] In U.S. Pat. No. 6,163,947, Coniglione, issued Dec. 26, 2000, andincorporated herein by reference, a string of hollow seeds described inU.S. Pat. No. 5,713,828, issued Feb. 3, 1998, also incorporated hereinby reference, are strung onto a thin strand of suture material to forman array of seeds. This string of seeds is delivered into the tumor siteplaced within a hollow needle. Since the hollow lumen of the seeds aresubstantially smaller in diameter in relation to the outside diameter ofthe seed body, the string of suture material must be substantiallysmaller in diameter than the seeds themselves. The resulting diameter ofthe suture makes the suture axially weak and the suture can fold upbetween the seeds within the needle lumen as pressure is applied on theproximal end of the strand within the needle. Thus the difference indiameter between the seed and the thin suture material makes theassembly susceptible to collapse from axial force applied on theproximal end, resulting in jamming of the assembly within the needlelumen and/or the assembly not maintaining the proper desired spacingbetween radioactive seeds as the assembly is expelled into the treatmentsite.

[0013] One relevant reference discloses modification of the needlestructure to include a reloadable cartridge. In such reference theneedle is inserted and as a cartridge of seeds is emptied, the plungerof the device is withdrawn and a new cartridge containing radioactiveseeds is loaded into the syringe (Moore, U.S. Pat. No. 4,086,914, issuedMay 2, 1978). Another reference offers a device for implantingindividual seeds in a planar dispensing device with multiple needles toensure accurate placement of the seeds relative to one another and thetreatment site (Kirsch, U.S. Pat. No. 4,167,179 issued September 1979).Another reference disclosed a shielding devices for bead strands whichprevents radiation exposure for health care personnel performingtreatment with the radioactive seeds (Windarski, U.S. Pat. No. 4,509,506issued April 1985). All of the above references are incorporated hereinby reference.

[0014] In another technique for treating tumors disclosed in U.S. Pat.No. 5,460,592 and incorporated herein by reference, seeds are held in awoven or braided bio-absorbable carrier such as a braided suture. Thecarrier with the seeds laced therein is then secured in place to form asuitable implant. This braided assembly exhibits many drawbacks, as andwhen the braided assembly is placed into the tumor. The needle thatcarries the braided assembly must be blocked at the distal end toprevent body fluids from entering the lumen. If body fluid reaches thebraided assembly while the assembly is still in the lumen of the needle,the braided assembly can swell and jam in the lumen. Because theassembly is made of a braided tubular material, it is difficult to pushthe assembly out of the needle. As the needle is withdrawn from thetumor, pressure on the proximal end of the braided assembly causes thebraid to expand and jam inside the lumen of the needle. Finally, if thebraided strand is successfully expelled from the needle, the relativespacing of the seeds may not be maintained, if the braided material hascollapsed.

[0015] Other references that address such implants and materials includethe following, all of which are incorporated herein by reference.

[0016] U.S. Patent Documents

[0017] U.S. Pat. No. 1,578,945 issued January 1923 to Withers

[0018] U.S. Pat. No. 2,067,589 issued January 1937 to Antrim

[0019] U.S. Pat. No. 3,351,049 issued November 1967 to Lawrence

[0020] Medi-Physics brochure entitled “I-125 Seeds.RTM. In Carrier”,Model No. 6720.

[0021] Medi-Physics brochure entitled “I-125 Seed.RTM. Source Model6711”.

[0022] Martinez et al., Int. J. Radiation Oncology Biol. Phys., vol. 5,No. 3, March 1979, pp. 411-413.

SUMMARY OF SOME OF THE ASPECTS OF THE INVENTION

[0023] Accordingly, the present invention cures and addresses thedisadvantages exhibited in the prior art devices and implants. What isdesired is to provide a bio-absorbable carrier material having seedsdisposed within the material, with the seeds being accurately spaced apredetermined distance from one another, with the seeds repeatablymaintaining that spacing, even after being introduced into the body.

[0024] It is further desired that an elongated member with seeds besufficiently rigid axially to allow expulsion of the member whilemaintaining the spacing between seeds, and that the member be flexibleand pliable enough to move with the tissue as the tissue shrinks back topre-operative size.

[0025] Accordingly, some of the objectives of the present inventioninclude providing an elongated member with seeds dispersed throughout,which obviates the aforementioned disadvantages and allows placement ofthe seeds in accurate positions to provide the desired interstitialradiation dose to the location derived from a preoperative dosimeterplan.

[0026] A further object of the present invention is to provide adelivery system for interstitial radiation therapy, which is faster andeasier to use than prior art systems.

[0027] Another object of the present invention is a delivery system thatcauses a minimum of trauma to tissue.

[0028] Yet another object of the present invention is a delivery systemthat allows for control of the radiation dosage given the tissue. Stillfurther objects of the present invention is a delivery system that canbe used and placed with precision, and that maintains the position ofthe implant after the implantation, until the bio-compatible materialdissolves and the seeds have become inert. In another aspect thebio-compatible material is selected to absorb about when the half-lifeof the radioactive seeds is reached.

[0029] A further aspect is to have the implant be echogenic.

[0030] In accordance with an embodiment of the invention, the deliverysystem comprises a substantially axially stiff and longitudinallyflexible elongated member that is bio-absorbable in living tissue. Themember has a length that greatly exceeds its width or diameter. Theelongated member has a plurality of radioactive seeds dispersed thereinin a predetermined array.

[0031] In another embodiment, the substantially axially stiff andlongitudinally flexible elongated member comprises a single continuousmonofilament element of bio-compatible material that has a plurality ofseed sources molded therein. The bio-compatible material can bepreferably a bio-absorbable polymer or copolymer material thatencapsulates the plurality of radioactive seeds.

[0032] A further embodiment of the invention is characterized as asubstantially constant diameter solid elongated matrix member of abio-absorbable polymer with seeds positioned therein at predeterminedspacing along its length, whose diameter is a close fit to the needlelumen, thus preventing collapse as axial force is applied on theproximal end of the elongated matrix member. The space between the seedsources is maintained throughout the insertion and expulsion of theelongated matrix member. The diameter of the polymer between the seedsmay be slightly reduced in diameter in relation to the overall diameterof the elongated matrix member, but is of sufficient diameter so as tonot allow collapse of the matrix member within the needle lumen.

[0033] The present embodiment of the invention further allows forvariation in any spacing between seeds, as the semi-rigid, deflectingelongate member could be produced under a doctor's prescription for eachpatient, with optimal seed distribution for a particular patient'streatment program.

[0034] This one object of the invention is to provide an implant thatcan be custom made as specified by a prescription for an individualpatient.

[0035] Further aspects, objects, advantage and embodiment of theinvention can be understood from the specification, the figures and theclaims.

DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is an enlarged side view of an embodiment of thetherapeutic implant of the invention.

[0037]FIG. 2 is an enlarged view of a cross section of an embodiment ofthe therapeutic implant of the invention of FIG. 1.

[0038]FIG. 3 is an enlarged side view of the brachytherapy deviceincluding the implant of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0039] In accordance with an embodiment of the invention, asubstantially axially, semi-rigid and longitudinally flexible elongatedmember made of material, which is bio-absorbable in living tissue, isprovided for insertion in tumors. A plurality of radioactive seeds areencapsulated and positioned in a predetermined array in the member inthe desired spaced relationships.

[0040] The seeds can be of various types having low energy and lowhalf-life such as Iodine seeds, known as I-125 seeds, consisting of awelded titanium capsule containing iodine 125 absorbed on a silver rod,or Palladium 103 seeds. Examples of radioactive seeds used tomanufacture the therapeutic element appear in Table 1 below. TABLE 1Seed Manufacturers and Common Types of Seeds. PART NUMBER MANUFACTURERSEED NAME IODINE¹²⁵ 80040-A Amersham 6702 OncoSeed 80040-B Amersham 6711RAPID Strand 80040-C North American Scientific IoGold 80040-D BestIndustries BEST Iodine-125 80040-E Bebig Symmetra 80040-F MillsBiopharmaceuticals ProstaSeed 80040-G Syncor PharmaSeed 80040-HInternational Isotopes IsoStar 80040-I Implant Sciences I-Plant 80040-JInternational Brachytherapy InterSource-125 80040-K Source Tech STM 125180040-L DRAXIMAGE, Inc. BrachySeed PALLADIUM¹⁰³ 80035-A North AmericanScientific Pd Gold 80035-B Theragenics Theraseed 200 80035-C BestIndustries BEST Palladium-103 80035-D International BrachytherapyInterSource 103

[0041] Additionally, seeds can be manufactured using iridium 192, cesium131, gold 198, yttrium 90 and phosphorus 32. Further radioactiveisotopes used to manufacture seeds are not limited to these examples,but can include other sources of different types of radiation. Inaddition it is to be understood that other types of seeds can be used.In particular, seeds such as those described in U.S. Pat. No. 6,248,057,which patent is incorporated herein by reference and which is entitledAbsorbable Brachytherapy and Chemotherapy Delivery Devices and Methods,can be used with the present invention. These seeds include radiationdelivery devices, drug delivery devices, and combinations of radiationand drug delivery devices in the form of beads, seeds, particles, rods,gels, and the like. These particular seeds are absorbable wherein theradiation element or drug delivery element is contained within, forexample, absorbable polymers such as those listed below or in theabove-referenced patent. In such seeds, the bio-absorbable structure canhave a predefined persistence which is the same as or substantiallylonger than a half life of the radioactive element contained in thebio-absorbable structure. These above bio-absorbable seeds can be usedin the same manner as the seeds described herein with respect to theinvention.

[0042] The substantially axially, semi-rigid, and longitudinallyflexible elongated member may be made of any of the natural and/orsynthetic bio-compatible and bio-absorbable materials. Natural andsynthetic polymers and copolymers can be used. Examples of syntheticbio-absorbable polymer materials are the polymers and copolymers ofglycolide and lactide, polydioxanone and the like. Such polymericmaterials are more fully described in U.S. Pat. Nos. 3,565,869,3,636,956, 4,052,988 and European Patent Application 30822 all of whichare incorporated herein by reference. Specific examples ofbio-absorbable polymeric materials that can be used to produce thesubstantially axially stiff and longitudinally flexible elongated memberof embodiment of the present invention are polymers made by ETHICON,Inc., Somerville, N.J., under the trademarks “MONOCRYL” and “MAXON”which material is incorporated herein by reference.

[0043] Table 2 below provides examples of polymers (and manufacturers)suitable for use in producing embodiments the therapeutic member of theinvention. A further discussion of such biodegradable polymers can befound in an article by John C. Middleton and Arthur J. Tipton entitled“Synthetic Biodegradable Polymers as Medical Devices,” published March1998 in Medical Plastics and Bio-materials which article is incorporatedherein by reference. TABLE 2 Biodegradable polymers, properties anddegradation time. MELTING GLASS- DEGRADATION POLY- POINT TRANSITIONMODULUS TIME MER (° C.) TEMP (° C.) (Gpa)^(a) (MONTHS)^(b) PGA 225-23035-40 7.0  6 to 12 LPLA 173-178 60-65 2.7 >24 DLPLA Amorphous 55-60 1.912 to 16 PCL 58-63 (−65)-(−60) 0.4 >24 PDO N/A (−10)-0 1.5  6 to 12 PGA-N/A N/A 2.4  6 to 12 TMC 85/15 Amorphous 50-55 2.0 5 to 6 DLPLG 75/25Amorphous 50-55 2.0 4 to 5 DLPLG 65/35 Amorphous 45-50 2.0 3 to 4 DLPLG50/50 Amorphous 45-50 2.0 1 to 2 DLPLG

[0044] The final hardness of the polymer of elongate member shouldpreferably be in a range from 20 to 80 durometer and more preferably inthe range of 20-40 durometer. The bio-absorbable material shouldpreferably be absorbed in living tissue in a period of time of fromabout 70 to about 120 days, but can be manufactured to be absorbedanywhere in a range from 1 week to 1 year, depending on the therapeuticplan for each specific patient Preferably the bio-absorbable material isselected to absorb about when the half-life of the radioactive seeds isreached.

[0045] The member or strand is fashioned with a manufacturing methodknown as insert or compression molding. The radioactive seeds are placedinto a fixture that spaces the seeds at the appropriate intervals in acavity that is shaped to the desired final dimensions of the elongatedmember. All the spacings can be of different lengths, if thepreoperative therapeutic plan so specifies. The synthetic polymer isintroduced into the mold at a temperature that is above the melt pointof the polymer. The polymer flows around the seeds within the cavity,surrounds the seeds and fills in the spaces between the seeds. After themold has cooled, it is disassembled, and the finished elongated memberis removed. Because the polymer flows at temperatures significantlygreater than 250° F., the therapeutic element can easily be steamsterilized before implantation.

[0046] As specified above, the elongated member encapsulatingradioactive seeds may be fashioned using compression molding techniques.Compression molding forms the molded piece in a two part mold where thepolymer material is placed within the cavities of the mold in a liquidstate. The seeds are placed in position within the cavities filled withthe polymer and the mold is closed and compressed, then cooled to form apiece that conforms to the shape of the closed cavity.

[0047] The manufacturing process also can make the member echogenic. Inthe case of the molding of the elongated member, air can be entrapped inthe polymer material. During the cooling stage of the molding process,the mold is placed in a vacuum chamber and the air in the chamber isevacuated. This causes the entrapped air in the mold to come out ofsolution from the polymer, and as the mold cools, this air is entrappedwithin the cooling polymer in the form of minute bubbles suspended inthe plastic.

[0048] Air is a strong reflector of ultrasound energy, since theinherent impedance of air is many times greater than body tissue. Whenthe elongated member is introduced into the body and imaged withultrasound, the elongated member is clearly visible in the resultingimage, and is thus echogenic.

[0049] The resulting elongated member is now a single solid monofilamentof the polymer with the seeds spaced within the monofilament andencapsulated at the appropriate intervals. The member is generally veryaxially flexible such that it can be bent back upon itself in a circlewithout kinking. However, the member has sufficient column strengthalong its longitudinal axis so that the member can be urged out of ahollow needle without the memberfolding upon itself. Again, theintervals can be selected to be any distance or combination of distancesthat are optimal for the treatment plan of the patient.

[0050] In FIG. 1, the therapeutic elongated element or member or matrixor strand 10 is displayed having the semi-rigid, radially flexiblepolymer 12 and the radioactive seeds 14. As can be seen in FIG. 1, thepolymer fills the spacing segments 16 in a contiguous manner to fashionthe total elongate member.

[0051]FIG. 3 shows a side view of the brachytherapy device 20. Theneedle 22 is shown partially broken away and has a sheath component 24,and is loaded with the therapeutic element or member 10. The beveled end26 of the needle 22 is plugged with a bio-compatible substance 28. Theplug prevents fluids and tissue from entering the needle and coming incontact with the member 10 prior to the placement of the member orstrand 10 adjacent the tumor. The plug 28 can be made out of a bone waxor can be made of one of the bio-absorbable polymers or copolymerslisted herein. Further the plug can be the end of the member or strand10 that is heated and reflowed after the strand or member is insertedinto the needle. A stylet or stylus 30 is inserted into the needle untilit meets the therapeutic element or member 10. Then the needle 22 isinserted into the site and the therapeutic member 10 is graduallyextruded from the needle via the static force of the stationary stylus30, as the needle 22 is pulled back.

[0052] Based on the above it is evident that the present inventionprovides for an embodiment having an elongated member which is comprisedof a biodegradable polymer which encapsulates a plurality of spacedradioactive therapeutic seeds. The seeds can be spaced in custom mannerso that each member or strand is designed for the particular patient.That is to say that the spacing between each seed pair in a strand ormember can be different for each seed pair. Further each individualstrand can have an entirely different seed spacing pattern than the nextstrand or member. Characteristically or typically for a surgicalprocedure, up to twenty-five of such strands or members are used toencircle the organ or tumor that is affected.

[0053] Further such an arrangement provides for a strand or member thatis stiff along its longitudinal axis. That is to say that the strand ormember has column strength or stiffness while the strand or member isflexible in the direction which is radial or substantially perpendicularto the longitudinal axis. Accordingly the strand or member in apreferred embodiment is able to bend back upon and touch itself, whenformed in a characteristic length.

[0054] In other embodiments, the strand or member can be made with theincorporation of drugs and/or hormones and/or other therapeutics whichare embedded in or formed in the polymer and/or seeds. Thus theembodiment of the invention can deliver not only radioactive seeds, butsuch therapeutic drugs, hormones and othertherapeutic devices. Inaddition the strand or member can deliver heated seeds such as providedby ATI Medical. Then seeds can be preferably heated to from about six(6) degrees centigrade to about seventy (70) degrees centigrade prior tobeing inserted into a patient in a preferred embodiment. ATI Medical islocated at (www.ATImedical.com), and reference to such heated seeds isincorporated herein by reference.

[0055] It should be understood that other seed types can be used withthe present invention. Thus for example in addition to the aboveencapsulated seeds, seeds which are made of radioactive or coiled wirescan be embedded in the polymer and be within the spirit and scope of theinvention. These seeds can be individual seeds which are spaced within apolymer or a continuous seed which extends the length of the strand ormember.

[0056] Further to the invention, as discussed above, it should beunderstood that the strand or member can be made echogenic by theincorporation of, for example, air bubbles 32 in the polymer spacesbetween the seeds, as can be seen in FIGS. 1 and 3. These air bubbles orpockets can be formed in the polymer in ways identified above and otherways known to one of skill in the art.

[0057] According to the above, the advantages of the improved deliverysystem submitted of the present invention are:

[0058] 1. The substantially axially stiff and longitudinally flexibleelongated member allows controlled placement of the plurality ofradioactive seeds that are encapsulated and positioned in apredetermined array in the member without migration of the individualradioactive seeds during the time the seeds are treating the tumor.

[0059] 2. The fixed linear positioning of the seeds minimizes “hot” and“cold” radiation spots due to undesirable movement of the seeds.

[0060] 3. The normal tissue is spaced away from the seed surface by thethickness of the body of polymer, to decrease necrosis from a high localdose.

[0061] 4. The axial stiffness of the elongated member allows theelongated member to be urged out of the needle as the needle iswithdrawn, without the member jamming in the needle, by collapsing orexpanding as the needle is withdrawn from the tumor site.

[0062] 5. The longitudinal flexibility of the elongated member allowslocational accuracy to be maintained as the gland shrinks topre-procedural size, as the swelling that occurs during tissuedisruption and needle manipulation recedes.

[0063] 6. Increased speed of implant resulting in reduced surgical timeand health care provider radiation exposure.

Method of Delivering Customized Strands and/or Members per a TherapeuticPrescription

[0064] As is known in the industry, there is software which can be usedto provide branchytherapy treatment planning guides which are customizedfor each individual patent. Such software is provided by Rossmed whichis located at Ross Medical, 7100 Columbia Gateway Drive, Suite 160,Columbia, Md. 21046. This particular software, which is incorporatedherein by reference, is known as the Strata suite, which software helpsphysicians to develop and visualize low dose rate brachytherapytreatment plans for treating malignant tumors in human tissue. Thetreatments entail the use of radioactive seed sources which areimplanted adjacent to the malignant tissue. The Strata software usesimaging to create a three dimensional reconstruction of the patient'sanatomy. The software is able to plan the placement of the seeds withinthe target. The radiation dose that is delivered to the target can becomputerized and visualized using the software. The software can thenspecify an optimal number of strands or members along with optimal seeddosages and spaces between seeds. At times the loading plans sospecified cannot be optimized by the physician in preparing the seed andspacer loads for the needles, as the spacers come in only predefinedlengths.

[0065] Accordingly with the present invention, the software can be usedto prepare a prescription which optimizes the number of members orstrands, and placement and spacing of seeds for each of the strands ormembers. This optimization plan can then be sent to a manufacturingsite. By using the techniques of an embodiment of the present invention,an optimized strand or member can be created with the specified numberof seeds and the specified distances between each seed pair. Once thisprescription is filled at the manufacturing site, the custom strand ormember can be sent back to the physician for treatment of the patient.With such an arrangement, radiation patterns can be optimallyestablished for the treatment of each patient. Further the preparationtime for the physician is greatly diminished as the physician does nothave to hand assemble and hand load the seeds and spacers into theneedle.

[0066] Further even if the physician were to use a prescription providedby the above software, with prior manufacturing techniques, thephysician would only receive from the manufacturing facility a strand ormember which has seeds spaced at predefined intervals, which are thelengths or the pre-manufactured spacers. Accordingly optimal treatmentas provided by the custom strands or members manufactured according tothe present invention could not be realized.

[0067] Additional aspects, objects and advantages of the invention canbe obtained through a review of the appendant claims and figures. It isto be understood that other embodiments can be fabricated and comewithin the spirit and scope of the claims and the invention.

We claim:
 1. A therapeutic element comprising: an elongate solid member;radioactive seed elements; said radioactive seed elements dispersedwithin said elongate solid member.
 2. The therapeutic element set forthin claim 1 wherein said elongate solid member is axially rigid andradially flexible.
 3. The therapeutic element set forth in claim 1wherein said elongate solid member is sufficiently axially rigid toprevent jamming or collapsing while being pushed out of a needle.
 4. Thetherapeutic element set forth in claim 1 wherein said elongate solidmember has sufficient radial flexibility to maintain locational accuracyrelative to a tumor target as said tumor target shrinks in size.
 5. Thetherapeutic element set forth in claim 1 wherein the thickness of saidelongate solid member around said radioactive seeds is sufficient todecrease normal tissue necrosis from a high local dose of radiation. 6.The therapeutic element set forth in claim 1 wherein said elongate solidmember is longitudinally flexible.
 7. The therapeutic element set forthin claim 1 wherein said elongate solid member is impregnated with ahormone.
 8. The therapeutic element set forth in claim 1 wherein saidelongate solid member is impregnated with a drug.
 9. The therapeuticelement set forth in claim 1 wherein said radioactive seed elements arepositioned at various intervals along the length of said elongate solidmember.
 10. The therapeutic element set forth in claim 1 wherein saidradioactive seed elements contain a hormone.
 11. The therapeutic elementset forth in claim 1 wherein said radioactive seed elements contain adrug.
 12. The therapeutic element set forth in claim 1 wherein saidradioactive seeds contain a compound or element that emits photonicradiation having a low energy and a short half-life.
 13. The therapeuticelement set forth in claim 1 wherein said radioactive seeds contain anisotope consisting of the group iodine 125, palladium 103, iridium 192,cesium 131, gold 198 yttrium 90 and phosphorus
 32. 14. The therapeuticelement set forth in claim 1 wherein said elongate member is composed ofa bio-absorbable material.
 15. The therapeutic element set forth inclaim 1 wherein said elongate member is composed of a bio-absorbablematerial absorbed by living tissue within about 70 to 120 days.
 16. Thetherapeutic element set forth in claim 1 wherein the bio-absorbablematerial is selected from the group consisting of polymers andcopolymers of glycolide, lactide and polydiaxanone.
 17. The therapeuticelement set forth in claim 1 wherein said elongate solid member isechogenic.
 18. The therapeutic element set forth in claim 1 wherein saidelongate solid member has air bubbles.
 19. The therapeutic element setforth in claim 1 wherein said elongate solid member is laterallyflexible.
 20. A therapeutic element comprising: an elongate, axiallyrigid and radially flexible member; radioactive seed elements; saidradioactive seed elements dispersed within said elongate member.
 21. Thetherapeutic element set forth in claim 20 wherein said axially rigid andradially flexible member is continuous.
 22. A therapeutic elementcomprising: an elongate axially rigid and radially flexible member;radioactive seed elements; hormone impregnated seed elements; saidradioactive seed elements and said hormone impregnated seed elementsdispersed within said elongate axially rigid and radially flexiblemember.
 23. The therapeutic element set forth in claim 22 wherein saidaxially rigid and radially flexible member is continuous.
 24. Atherapeutic element comprising: an elongate axially rigid and radiallyflexible member; radioactive seed elements; drug impregnated seedelements; said radioactive seed elements and said drug impregnated seedelements dispersed within said elongate axially rigid and radiallyflexible member.
 25. The therapeutic element set forth in claim 24wherein said axially rigid and radially flexible member is continuous.26. A therapeutic element comprising; an elongate, axially rigid andradially flexible member; one of a hormone and a drug; said one ofhormone and said drug implanted in the elongate axially rigid andradially flexible member.
 27. The therapeutic element set forth in claim29 wherein said one of a hormone and a drug is dispersed along thelength of said elongate, axially rigid and radially flexible member. 28.A therapeutic element comprising: an elongate axially rigid member; saidelongate axially rigid member not having sufficient rigidity to bedriven into a tumor without deflection; radioactive seed elements; saidradioactive seed elements dispersed within said elongate solid member.29. A brachytherapy device comprising: a therapeutic element, includingan elongate, axially rigid and radially flexible member; a needle with alumen; a plug in the end of said needle; wherein said therapeuticelement is positioned inside said lumen of said needle.
 30. Thebrachytherapy device set forth in claim 29 wherein said elongate,axially rigid and radially flexible member is continuous.
 31. Thebrachytherapy device set forth in claim 29 wherein said elongate solidmember is a close fit to the needle lumen.
 32. The brachytherapy deviceset forth in claim 29 wherein the fit between said elongate solid memberand said needle prevents collapse of said therapeutic element as saidtherapeutic element is passed through said needle.
 33. The brachytherapydevice set forth in claim 29 wherein said plug is bio-compatible.
 34. Amethod for making a therapeutic element comprising, in any order:dispersing radioactive seed elements within a molding cavity; andfilling the molding cavity with a bio-absorbable polymer;
 35. The methodfor making a therapeutic element set forth in claim 34 wherein saidmolding cavity is shaped to the desired final dimensions of saidtherapeutic element.
 36. The method for making a therapeutic element setforth in claim 34 wherein said molding cavity spaces said radioactiveseeds at appropriate intervals.
 37. The method for making a therapeuticelement set forth in claim 34 wherein said polymer is introduced intosaid mold at a temperature greater than the melt point of said polymer.38. The method for making a therapeutic element set forth in claim 34wherein said polymer surrounds said radioactive seeds.
 39. The methodfor making a therapeutic element set forth in claim 34 wherein saidpolymer fills the spaces between said seeds.
 40. The method for making atherapeutic element set forth in claim 34 wherein said bio-absorbablepolymer is impregnated with a hormone.
 41. The method for making atherapeutic element set forth in claim 34 wherein said bio-absorbablepolymer is impregnated with a drug.
 42. A method of brachytherapycomprising: loading a needle with a therapeutic device; inserting saidneedle into the therapeutic site into the most distal location from theinsertion point; inserting a stylet into said needle; gradually pullingon said needle while maintaining the stylet stationary relative to theaxial movement of said needle; and dispensing said therapeutic device.43. The method of brachytherapy set forth in claim 42 wherein theoverall diameter of said therapeutic element is sufficient to preventcollapse within the needle lumen.
 44. The method of claim 43 whereinsaid therapeutic device is an elongated solid member having spacedradioactive seeds.
 45. The method of claim 43 wherein said therapeuticdevice is an elongated axially rigid and radially flexible member havingspaced apart radioactive seeds.
 46. The method of claim 43 wherein saidtherapeutic device is an elongated member formed of a bio-absorbablematerial into which are positioned a plurality of spaced apartradioactive seeds.
 47. The method of claim 43 wherein said therapeuticdevice is an elongated member is comprised of a plurality of spacedapart radioactive seeds which are encapsulated in a bio-absorbablematerial.
 48. The method of claim 47 wherein said bio-absorbablematerial is a polymer.
 49. The element of claim 1 wherein said memberhas a durometer in the range of about 20 to about
 80. 50. The element ofclaim 1 wherein said member has a durometer in the range of about 20 toabout
 40. 51. The element of claim 20 wherein said member has adurometer in the range of about 20 to about
 80. 52. The element of claim20 wherein said member has a durometer in the range of about 20 to about40.
 53. The element of claim 28 wherein said member has a durometer inthe range of about 20 to about
 80. 54. The element of claim 28 whereinsaid member has a durometer in the range of about 20 to about
 40. 55. Aprescription method of treating tissue comprising the steps of: firstcreating a tissue treatment plan for the tissue to be treated, whichtreatment plan specifies the a number and spacing of treatment seeds tobe provided in a strand; and second creating a treatment strand bymolding treatment seeds in a material.
 56. The method of claim 55wherein: said first creating step is performed by a person treating apatient; and said second creating step is performed by an entity thatfills prescriptions by forming the strand, which entity fillsprescriptions from a plurality of patients.
 57. The method of claim 55wherein: wherein said first creating step specifies radioactive seedsand optimal spacings between each pair of seeds; and wherein said secondcreating step creates strands to the specified optima spacingsprescribed.
 58. The method of claim 57 wherein: said second creatingstep is performed positioning radioactive seeds in a mold at the optimalspaces and pouring in a material to mold the radioactive seeds in place.59. The method of claim 58 wherein: said material that is poured is abio-absorbable material.
 60. The method of claim 59 wherein: saidmaterial that is poured in is a polymer material.
 61. The method ofclaim 55 wherein: said first creating step uses imaging devices forcreating a treatment plan.
 62. The method of claim 55 including:receiving said treatment strand and implanting the treatment strandadjacent to the tissue to be treated.
 63. The method of claim 55including the step of using heated treatment seeds.
 64. The method ofclaim 42 including the step of using heated treatment seeds.
 65. Thetherapeutic element set forth in claim 1 wherein said elongated memberis composed of a bio-absorbable material which is absorbed when thehalf-life of the radioactive seed elements is reached.
 66. Thetherapeutic element set forth in claim 20 wherein said elongated memberis composed of a bio-absorbable material that is absorbed when thehalf-life of the radioactive seed elements is reached.
 67. Thetherapeutic element set forth in claim 28 wherein said elongated memberis composed of a bio-absorbable material that is absorbed when thehalf-life of the radioactive seed elements is reached.
 68. Thetherapeutic element of claim 1 wherein said therapeutic element is steamsterilizable.
 69. The therapeutic element of claim 20 wherein saidtherapeutic element is steam sterilizable.
 70. The therapeutic elementof claim 22 wherein said therapeutic element is steam sterilizable. 71.The therapeutic element of claim 24 wherein said therapeutic element issteam sterilizable.
 72. The method of claim 42 wherein the therapeuticdevice is steam sterilized prior to usage.
 73. The therapeutic elementof claim 1 wherein the radioactive seed element is bio-absorbable. 74.The therapeutic element of claim 20 wherein the radioactive seed elementis bio-absorbable.
 75. The therapeutic element of claim 1 wherein theradioactive seed element also contains a drug and wherein the seedelement is bio-absorbable.
 76. The therapeutic element of claim 20wherein the radioactive seed element also contains a drug and whereinthe seed element is bio-absorbable.
 77. The therapeutic element of claim26 wherein said one of said hormone and said drug is encapsulated in abiodegradable seed.
 78. The therapeutic element of claim 26 wherein saidone of said hormone and said drug is encapsulated in a biodegradableseed along with radioactive elements.